let createError = require('http-errors');
module.exports = function(req, res, next) {
  // next(createError(404));
  if (req.xhr) {
    return res.status(404);
  }

  res.render('error-404.jade',{//这里的.jade可以去掉
    tit: "404",
    message: "抱歉，页面不存在!"
  });
};